Many circuit, such as various processing units, routinely have different voltage requirements based on operating modes. These voltage changes are generally controlled by voltage identification (VID) signals or VID codes. Many circuits, through, use multiple pins for these types of controls, but it is desirable to reduce the number of pins to lower cost. Some examples of conventional circuits are: European Patent No. 0872790; U.S. Pat. No. 5,905,370; U.S. Pat. No. 5,943,227; U.S. Pat. No. 6,192,420; U.S. Pat. No. 6,625,757; U.S. Pat. No. 6,772,356; U.S. Pat. No. 6,798,180; and U.S. Patent Pre-Grant Publ. No. 2002/0194516.